ENTOMOLOGY

380 SANITARY ENTOMOLOGYPeriplaneta a'tWltralasiae (Fabricius) BurmeisterThis species is of the same general size and appearance as americanaand has practically the same habits. It is readily distinguishable fromthat species by the elytra, which have an elongate yellowish spot borderingthe outer margin next the pronotum. The yellowish margins ofthe pronotal disk is in greater contrast to the more clearly delineatedcentral portion than in americana and the' general size is also somewhatless.This roach is found mostly in warmet; regions and is more often thanany other species reported as' injurious to plants in greenhouses, conservatories,etc..REMEDIESRemedies galore, good, bad, and indifferent, mostly the latter, havebeen recommended for use against roaches. No extended discussion ofthe divers methods proposed for the discouragement or destruction ofthese household pests will be here entered into. Only a few of the morepromising methods of eradication will lie considered.Hydrocyanic Acid GasF'l.llTnigatio'l&In extreme infestation the best method of ridding a premise ofroaches is by fumigation, the best fumigant being hydrocyanic acid gasat the rate of 10 ounces per 1,000 cubic feet for one hour. While thoroughlyeffective, this treatment involves considerable cost, and, o~ing toits extremely dangerous qualities, necessitates extreme care in its application.Before attemptilng fumigation with this POISONOUS gas, detaileddirections shomO, be carefuJ),y studied. Such directions are givenin the lecture on the control of human lice (p. 3~4).Carbon BisuJ.phideA fumigant less dangerou,s to use than the above, but one requiringmuch precaution because of its inflammability, is carbon bisulphide. Thishighly volatile material distributed in open vessels, one pound to each1,000 cubic feet of space, will destroy roaches, but the rooms fumigatedmust be ones that can be very tightly sealed up, as indeed must be the caseIn any fumigation. This method is well adapted for use in the holds of shipsand other vessels. A fumigation of twenty-four hours will kill all verminin a tightly sealed room. 'I'he violently eIJJploaive nature of this materialnecessitates extreme care in its use. No fire of any kind must be aboutwhen it is in use.